UNIVERSITY   OF   CALIFORNIA 

COLLEGE   OF   AGRICULTURE 

AGRICULTURAL    EXPERIMENT   STATION 

BERKELEY,   CALIFORNIA 


THE  RELATION  OF  RATE  OF  MATURITY 
TO  EGG  PRODUCTION 


MELVIN  W.  BUSTER 


BULLETIN  424 

May,  1927 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1927 


THE  RELATION  OF  RATE  OF  MATURITY  TO   EGG 

PRODUCTION 

MELVIN  W.  BUSTER* 


Ever  changing  economic  conditions  affecting  the  poultry  industry 
stimulate  a  constant  search  by  the  producer  of  market  eggs  for  means 
of  reducing  costs  of  production.  The  efficiency  of  the  producing 
units  is  a  very  important  factor  influencing  such  costs. 

Individual  hens  differ  in  egg-laying  performance,  and  there  are 
various  ways  of  detecting  the  efficiency  of  egg  production.  The 
culling  of  hens  after  the  first  season's  lay,  on  the  basis  of  physical 
indications  of  past  performance,  is  increasingly  recognized  as  good 
flock-management  practice.  Yet,  for  a  positive  test  of  egg-laying 
ability,  no  method  or  equipment  superior  to  the  trap  nest  has  been 
devised.  Trap-nesting  is  a  very  necessary  procedure  in  the  process 
of  developing  and  maintaining  better  producing  flocks.  Trap-nesting, 
however,  is  slow,  expensive,  and  usually  considered  feasible  only  for 
pedigree  breeding.  For  the  commercial  egg  producer,  a  quicker  and 
more  practical  method  of  eliminating  the  inefficient  egg  producers, 
before  they  have  been  maintained  at  a  loss,  is  highly  desirable. 

The  rate  of  maturity  in  pullets  supplies  a  basis  for  determining 
their  potential  egg-laying  ability  and  thereby  furnishes  a  means  of 
reducing  the  cost  of  egg  production.  Rate  of  maturity  affords  a 
gauge  which  makes  it  possible  to  eliminate  most  of  the  inferior  indi- 
viduals before  housing  space,  feed,  and  labor  have  been  used  in  deter- 
mining their  unprofitableness.  Consequently,  considerable  unneces- 
sary expense  may  be  avoided  by  intelligent  pullet  segregation  and 
culling -before  the  birds  have  actually  started  to  lay. 

Previous  Experimental  Data. — As  early  as  1915,  Rice2  published 
an  analysis  of  the  three-year  laying  records  of  169  White  Leghorn 
hens,  which  indicate  the  marked  correlation  between  earliness  of 
maturity,  on  the  one  hand,  and  the  rate  and  persistence  of  laying,  on 
the  other.  The  work  of  Kempster  and  Henderson,3  in  1920-21  and 
1922,  making  observations  on  230  White  Leghorn  pullets,  found  that 
those  laying  the  first  egg  when  less  than  175  days  of  age  gave  an 
average  production  of  168   eggs  the  first  year;  those  coming  into 


i  Extension  Specialist  in  Poultry. 

2  Eice,  J.  E.  Distribution  of  egg  production.  Cornell  Countryman,  12:5-8. 
1915. 

3  Kempster,  H.  L.,  and  E.  W.  Henderson.  Length  of  period  required  to  reach 
maturity  as  an  indication  of  future  egg  production.  Missouri  Agr.  Exp.  Sta.  Bui. 
189:48,  and  Bui.  197:74.     1922. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

laying  between  175  and  199  days  averaged  162  eggs;  200  to  224  days, 
153  eggs;  225  to  249  days,  146  eggs;  250  to  274  days,  125  eggs;  and 
275  to  299  days,  92  eggs.  In  1921,  Kennard4  published  a  comparison 
of  two  lots  of  fifty  birds  each  with  reference  to  egg  production,  mor- 
tality, and  the  number  of  culls  at  the  end  of  the  first  laying  year. 
Lot  1  included  the  fifty  earlier  maturing  pullets  from  a  flock  of  three 
hundred,  all  hatched  April  7,  1920;  Lot  2  was  made  up  of  the  fifty 
slowest  maturing  pullets  from  the  flock.  The  latter  were  in  good 
condition  but  backward;  no  weaklings  were  included.  A  partial 
summary  of  Kennard 's  results  is  presented  in  table  1. 

TABLE  1 

Comparison  of  Early  and  Late  Maturing  Pullets 

(Data  of  Kennard.) 


Lot 
number 

Average 
first  year  egg 
production 

Mortality 

Culls 

September, 

1922 

Margin  per  bird  over  cost  of  feed 

after  deduction  of  mortality 

and  culling  loss 

1 

2 

160 
118 

0 

7 

4 
17 

$4.04 
1.63 

Kennard  also  concluded  from  this  experiment  that  the  earlier 
maturing  pullets  attained  greater  body  weight  and  laid  relatively 
larger  eggs. 

Such  observations  are  suggestive  even  though  the  number  of  birds 
reported  upon  was  not  large,  and  they  were  not  kept  under  com- 
mercial conditions.  It  was  decided,  therefore,  to  undertake  pullet- 
segregation  tests  with  large  numbers  of  birds,  in  commercial  flocks 
of  Sonoma  County,  to  determine  the  importance  of  rate  of  maturity 
as  a  factor  in  commercial  flock  management. 


PULLET  SEGREGATION  TESTS   IN   SONOMA  COUNTY 

An  effort  was  made  to  secure  flocks  between  four  and  one-half  and 
six  months  of  age  in  which  from  5  to  10  per  cent  of  the  birds  were 
just  beginning  to  lay.  The  success  of  the  tests  of  necessity  depended 
on  the  careful  cooperation  of  the  flock  owners  in  maintaining  the 
segregation  and  in  keeping  accurate  records  of  production  and  mor- 
tality. It  is  not  to  be  supposed  that  the  results  recorded  are  perfectly 
accurate.  As  the  segregation  was  carried  out  it  is  not  improbable 
that  an  occasional  bird  from  an  earlier  maturing  group  escaped  into 
the  pen  of  later  maturing  birds,  or  the  reverse.    In  the  main,  however, 

4  Kennard,  D.  C.  Early  maturing  vs.  late  maturing  White  Leghorn  pullets. 
Ohio  Agr.  Exp.  Sta.  Mo.  Bui.  6:163-167.     1921. 


BUL.  424]       RELATION   OF  RATE  OF  MATURITY   TO  EGG  PRODUCTION  5 

the  cooperators  were  most  careful  and  conscientious,  and  it  is  believed 
that  the  results  recorded  are  truly  representative.  To  insure  the  value 
of  tests  conducted  and  to  guard  against  the  possibilities  of  errors  from 
various  causes,  these  tests  on  commercial  flocks  were  conducted  for  a 
period  of  three  years  and  on  eleven  different  farms. 

Basis  of  Segregation. — Each  pullet  was  handled  individually. 
Two  characteristics  were  considered  in  segregating  the  birds : .  first, 
size  and  weight,  and  second,  degree  of  sexual  maturity.  The  character- 
istics noted  as  indications  of  sexual  maturity  were  size  and  redness 
of  the  comb  and  wattles,  and  quality  and  extent  of  the  body  area 
between  the  pelvic  bones  and  between  the  pelvic  and  keel  bones.  Each 
flock  was  considered  as  a  unit  and  the  segregation  was  based  on  the 
individual  differences  between  the  birds  within  the  same  flock.  No 
weaklings  which  would  ordinarily  be  considered  as  culls  were  included 
in  the  later  maturing  group. 

FIEST  TEST,  1921-22 

On  July  19  and  21,  1921,  two  flocks  of  Single  Comb  White  Leg- 
horn pullets,  totaling  over  twelve  hundred  individuals,  were  segre- 
gated into  two  groups  each,  one  group  containing  the  earlier  matur- 
ing and  the  other  the  later  maturing  birds.  The  segregation  of  the 
flocks  was  supervised  by  R.  B.  Easson,  former  Extension  Poultry 
Specialist  of  the  University  of  California.  The  pullets  were  well 
grown  and  were  the  product  of  average  breeding  and  care.  There 
was  every  indication  that  these  flocks  were  developed  normally  and 
without  undue  stimulation  or  forcing  to  bring  them  into  laying  too 
soon  or  before  they  were  properly  developed.  Also,  there  were  no 
noticeable  retarding  influences.  Becween  5  and  10  per  cent  were 
beginning  to  lay  at  four  and  one-half  months  of  age. 

It  was  planned  that  the  tests  should  be  conducted  for  an  entire 
year.  However,  for  various  reasons  it  was  only  possible  to  secure 
a  record  of  three  months  and  ten  days  on  one  flock  and  five  months 
on  the  other. 

Results  of  First  Test. — The  two  flocks  were  segregated  into  approx- 
imately equal  numbers  of  early  and  late  maturing  pullets,  in  order 
to  accommodate  the  housing  space  of  the  cooperators.  Although  of 
different  duration,  the  two  records  were  combined  during  the  months 
of  August,  September,  and  October,  and  averages  figured  accordingly. 
The  purpose  of  this  was  to  present  a  composite  record  for  the  longest 
period  and  the  greatest  number  of  birds  possible.  The  total  number 
of  pullets  averaged  1,171  for  the  five  month  period,  August  to  Decern- 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


ber ;  493  in  the  earlier  maturing  group  and  678  in  the  later  maturing 
group.  During  the  five-month  period  the  earlier  maturing  pullets 
laid  48.5  eggs  per  pullet  as  compared  with  24.4  eggs  each  for  the 
later  maturing.  In  terms  of  value  of  eggs  based  on  current  Petaluma 
prices,  assuming  that  all  of  the  eggs  laid  by  both  groups  were  pullet 
eggs  (19  to  22  ounces  a  dozen)  the  earlier  maturing  pullets  returned 
a  profit  of  86%  cents  per  pullet  more  than  the  later  maturing  for 
the  five-month  period. 

TABLE  2 

Pullet-Segregation  Test,  1921 

Segregated  July  19  and  21,  1921,  at  4%  months  of  age. 

Total  average  number  of  pullets  for  five-month  period,  1171. 


Average  number  of  eggs  per  pullet 

Value  of 

Month 

Earlier  maturing 
(493  pullets) 

Later  maturing 
(678  pullets) 

Difference  in  favor 

earlier  maturing 

pullets 

gain  per 
pullet* 

August 

10.7 
13.1 
10.3 

8.2 
6.2 

3.0 
8.6 
7.9 
3.4 
1.5 

7.7 
4.5 
2.4 
4.8 
4.7 

(Cents) 

23.58 

September 

15.60 

October 

8.44 

November 

19.32 

December 

19.55 

Totals 

48.5 

24.4 

24.1 

86.49 

*  Value  of  eggs  based  on  assumption  that  all  eggs  were  pullet  eggs  (19  to  22  ounces  a  dozen). 

Table  2  indicates  production  during  each  month,  in  eggs  per  pullet, 
the  gain  in  eggs,  and  the  value  of  gain  of  the  earlier  maturing  pullets 
over  the  later  maturing  pullets. 

To  substantiate  the  assumption  that  these  pullets  were  normally 
matured  Single  Comb  White  Leghorn  pullets,  attention  is  directed 
to  the  fact  that  the  average  egg  production  of  these  flocks  during  their 
sixth  month  was  21  per  cent. 

The  production  curve,  figure  1,  shows  the  consistent  difference  in 
intensity  of  egg  production  between  the  earlier  and  later  maturing 
groups.  Also  the  more  sudden  and  much  greater  drop  in  production 
of  the  slower  maturing  group  in  the  molting  period  of  November 
and  December  is  quite  noticeable. 

Cost  Data. — During  the  same  year  cost  data  were  obtained  on 
one  flock  of  420  pullets  which  was  segregated  on  July  21  at  four  and 
one-half  months  of  age,  140  in  the  earlier  maturing  group  and  280 
in  the  later  maturing  group.  The  total  actual  expenditure  on  the 
420  pullets  up  to  eight  months  of  age  was  $484.66,  while  the  income 


BUL.  424]      RELATION   OF  RATE  OF  MATURITY  TO  EGG  PRODUCTION 


from  sale  of  eggs  was  $421.77.  This  particular  flock  at  eight  months 
of  age  had  been  carried  at  a  loss  of  $62.89  or  a  net  cost  per  pullet  at 
eight  months  of  15  cents.  However,  figured  on  the  basis  of  produc- 
tion from  the  different  units  of  earlier  and  later  maturing  pullets, 
the  more  rapidly  maturing  pullets  returned  a  profit  of  11  cents  per 
bird,  while  the  later  maturing  pullets  were  carried  at  a  loss  of  28 
cents  per  bird. 


SSS* 


Aug. 

Fig.  1. 


Seprk  Oct.  ftov.  Dec. 

-Illustrating  table  2.     Egg  production  per  pullet  in  first  test,  1921. 


SECOND   TEST,  1922-23 

The  results  secured  in  1921  appeared  to  be  sufficiently  interesting 
and  valuable  to  warrant  conducting  another  similar  test  on  a  larger 
scale  to  be  continued  if  possible  for  one  year.  Consequently  in  the 
summer  of  1922  seven  flocks  comprising  6,084  Single  Comb  White 
Leghorn  pullets  four  and  one-half  to  six  months  of  age  were  secured 
for  the  second  test. 

Purposes  of  Second  Test. — Purposes  of  the  second  test  were  four 
in  number: 

1.  To  secure  further  data  on  the  differences  in  laying  perform- 

ance between  earlier  and  slower  maturing  pullets. 

2.  To  secure  data  on  the  relative  mortality. 

3.  To  secure  accurate  cost  data. 


8 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


4.  To  get  some  idea  of  the  percentage  of  later  maturing  pullets, 
in  a  normally  maturing  commercial  flock,  which  might  profit- 
ably be  culled  out  and  disposed  of  at  four  and  one-half  to 
six  months  of  age. 
The  method  of  segregation  was  the  same  as  in  the  first  test. 
Results  of  Second  Test. — The  seven  flocks  were  segregated  during 
September  21,  1922,  as  follows :  five  flocks,  comprising  3,976  pullets, 
were  segregated  into  two  groups,  1,955  or  about  49  per  cent  in  the 


TABLE  3 

Pullet-Segregation  Tests,  1922-23 

Two  groups,  segregated  September  1  to  16,  average  age  five  months. 

Total  average  number  of  pullets,  3,557.  *  Four  flocks. 


Average  number  of  eggs  per  pullet 

Month 

Earlier  maturing 
(1,716  pullets)* 

Later  maturing 
(1,841  pullets)* 

Difference  in  favor 

of  earlier  maturing 

pullets 

September 

October 

November 

December 

January 

5. 
7.5 
7.4 
10.0 
15.2 
15.3 
18.8 
18.2 
19.0 
15.2 

.8 

3.2 

6.4 

9.4 

14.6 

13.9 

16.8 

13.8 

12.4 

12.3 

4.2 

4.3 

.6 

.5 

.6 

February 

1.4 

March  

2. 

April 

4.4 

May 

6.6 

June 

2.9 

Totals 

131.6 

103.6 

28.0 

Average  mortality 

14  per  cent 

20  per  cent 

6  per  cent 

*  The  total  number  of  pullets  and  the  number  in  each  group  refers  to  the  average  number  in  the 
test  throughout  the  ten  months  period. 

earlier  maturing,  and  2,021  or  51  per  cent  in  the  later  maturing 
group.  The  other  two  flocks  comprising  2,107  pullets  were  segre- 
gated into  three  groups,  704  or  33  per  cent  in  the  earliest  maturing 
group,  802  or  38  per  cent  in  the  medium-maturing  group,  and  601 
or  29  per  cent  in  the  latest  maturing  group. 

On  four  of  the  flocks  which  had  been  segregated  into  two  groups, 
careful  production  records  were  kept  for  ten  months  by  the  coopera- 
tors.  Table  3  gives  the  average  egg  production  per  pullet  and  the 
mortality  in  the  two  groups. 


BUL.  424]       RELATION  OF  RATE  OF  MATURITY  TO  EGG  PRODUCTION  9 

The  average  production  of  these  flocks  at  six  months  of  age  was 
17  per  cent. 

Figuring  all  costs  of  production  on  the  basis  of  60  per  cent  of 
the  total  cost  being  for  feed  and  on  the  local  prices  for  feed  and  eggs 
during  the  period  in  which  the  test  was  running  (using  Sonoma 
County  Farm  Bureau  Egg  Laying  Contest  costs  and  revenue  figures 
as  the  basis)  the  later  maturing  group  just  about  'broke  even,' 
whereas  the  earlier  maturing  group  returned  a  net  profit  of  approxi- 
mately 85  cents  per  pullet  over  cost  of  feed,  labor,  depreciation  on 
stock  and  equipment,  and  interest  on  investment. 


5*/>* 


Oct. 


Dec. 


Jan. 


Feb. 


Apr-. 


May 


Jun* 


Fig.    2. — Illustrating   table    3.      Egg    production    per    pullet   in   two-group 
segregation  of  the  second  test,   1922-23. 


Figure  2  demonstrates  very  strikingly  the  superiority  of  the 
earlier  maturing  over  the  later  maturing  pullets  in  egg-laying  ability. 
The  spread  between  the  curves  after  March  shows  this  very  con- 
clusively; the  later  maturing  were  quicker  to  break  and  drop  in 
production  as  well  as  being  slower  to  start.  Otherwise,  with  the 
exception  of  intensity,  the  trend  in  production  of  both  groups  is 
quite  similar  throughout  the  year. 

The  two  flocks  which  were  segregated  into  three  groups  each  were 
kept  for  a  similar  ten-month  period.  The  results  in  egg  production 
and  mortality  are  given  in  table  4. 

The  average  egg  production  of  these  flocks  at  six  months  of  age 
was  20  per  cent. 

Figuring  on  the  same  basis  as  before,  the  latest  maturing  groups 
in  the  flocks  were  run  at  a  loss  of  approximately  38  cents  a  bird,  while 


10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


the  medium  maturing  and  earliest  maturing  groups  returned  a  profit 
of  approximately  32  cents  and  $1.15  per  pullet  respectively. 

On  the  basis  of  egg  production,  although  there  may  have  been 
some  profitable  birds  in  the  latest  maturing  group,  there  can  be  little 
doubt  that  as  a  group  they  were  culls.  Even  though  this  group  rep- 
resented 29  per  cent  of  the  entire  flock  the  owner  would  have  lost 
less  money  had  he  disposed  of  them  at  the  time  of  segregation.     The 

TABLE  4 

Pullet-Segregation  Tests,  1922-23 

Three  groups,  segregated  September  1,  1922,  age  five  months,  twenty  days. 
Total  average  number  of  pullets,  2,039.     Two  flocks. 


Average  number  of  eggs  per  pullet 

Month 

Earliest  maturing 
(690  pullets) 

Medium  maturing 
(779  pullets) 

Latest  maturing 
(570  pullets) 

September 

October 

11.5 
12.5 
14.5 
12.9 
13.4 
14.2 
16.0 
15.5 
14.7 
13.8 

2.2 
8.6 

12.6 
11.3 
13.5 
13.1 
15.1 
15.0 
13.0 
9.8 

.3 
2.6 

November 

December 

January 

February 

March 

April 

May 

June 

10.3 
10.1 
11.8 
12.2 
12.5 
11.5 
10.0 
9.6 

Totals 

141.0 

114.2 

90.9 

Average  mortality 

3. 6  per  cent 

5. 3  per  cent 

9.0  per  cent 

remaining  birds,  in  the  earliest  and  medium-maturing  groups,  would 
no  doubt  have  given  better  results  because  of  decreased  congestion 
in  the  houses  and  yards. 

In  figure  3,  as  in  figure  2,  the  trend  in  egg  production  in  the 
earliest,  medium,  and  latest  maturing  groups  is  similar,  the  later 
maturing  groups  being  less  intensive  layers. 

In  studying  table  3  or  figure  2,  it  is  interesting  to  note  that  in  no 
month  did  the  later  maturing  pullets  lay  as  many  eggs  as  the  earlier 
maturing  groups.  Likewise,  in  the  three-group  segregation,  with  the 
exception  of  January,  when  the  production  per  pullet  in  the  medium- 
maturing  group,  was  0.1  per  cent  higher  than  in  the  earliest  maturing 
group,  the  later  maturing  groups  consistently  laid  less  eggs  than  the 
earlier  maturing  groups. 


BUL.  424]       RELATION  OF  RATE  OF   MATURITY  TO  EGG  PRODUCTION 


11 


The  figures  on  mortality  are  just  as  indicative  of  relative  quality 
although  possibly  less  accurate,  particularly  since  there  seems  to  be 
a  decided  difference  in  the  mortality  report  in  the  two  and  three-group 
segregations.  In  some  of  the  flocks  which  were  segregated  into  two 
groups  a  few  of  the  pullets  may  have  flown  over  to  other  pens  and 
were  consequently  charged  in  on  mortality.  Yet  it  is  believed  that 
the  degree  of  error  is  small  since  other  records  of  a  similar  nature 
have  shown  considerable  variation  in  mortality  on  different  ranches. 
In  this  connection  it  must  be  borne  in  mind  that  these  tests  were  not 


June 


Fig.  3. — Illustrating  table  4.     Egg  production  per  pullet  in  the  three-group 
segregation  of  the  second  test,  1922-23. 


conducted  under  what  might  be  considered  as  ideal  experimental  con- 
ditions. Nevertheless  the  figures  on  the  whole  can  be  considered 
reliable,  because  of  th'e  numbers  involved,  the  care  of  the  cooperators 
and  the  consistent  results.  Also  the  fact  that  the  tests  were  conducted 
on  commercial  plants  under  thoroughly  practical  conditions,  adds 
considerably  to  the  practical  value  of  the  records. 

Cost  Data. — One  of  the  cooperators  whose  flock  was  segregated 
into  three  groups  kept  careful  cost  data  on  each  group  for  eight  months 
of  the  ten.  During  the  other  two  months,  December  and  January, 
the  three  flocks  were  run  together  in  the  orchard  to  secure  green  feed 
and  were  again  segregated.  Records  on  the  flock  for  this  two-month 
period  were  not  included.  The  second  segregation  entailed  very  little 
extra  trouble  since  the  birds  in  each  of  the  three  groups  were  leg- 
banded  with  different-colored  leg  bands  at  the  time  of  the  first  segre- 
gation.    These  facts  made  complete  segregation  at  all  times  certain, 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


particularly  since  the  cooperator  was  very  careful.  Figure  4  shows 
the  cost  data  in  terms  of  feed  costs,  interest,  and  depreciation  on 
stock  and  buildings,  mortality,  gross  return,  and  net  profit  or  loss 


250  Edr/iesi-  Morx/r/ng        270  Medium-Mcrrunhg         /SO  Laresr  Maturing 
Pof/efc  -38.4  Per  Cen+         Pv//e-fs  -  41.5  Per  Cerrr        Pv/lars  -  ZOJ  Per  Gsrrf 

Fig.  4. — Cost  and  profit  data  (average  per  pullet)  in  one  flock  of  the  three- 
group  pullet  segregation,  1922-23.  The  flock  was  hatched  March  5,  and  segre- 
gated August  28 — age  5  months,  23  days.  The  item  "Interest  and  Depreciation" 
covers  both  stock  and  buildings. 

for  each  of  the  three  groups  of  earliest,  medium,  and  latest  maturing 
pullets,  for  the  eight  months  period. 

The  records  as  represented  in  figure  4  cover  a  total  period  of 
eight  months  and  include  all  of  the  main  costs  except  labor.     Had 


BUL.  424]      RELATION  OF  RATE  OF  MATURITY  TO  EGG  PRODUCTION  13 

the  cost  of  labor  been  included  the  loss  per  pullet  in  the  latest  matur- 
ing group  would  have  been  at  least  40  cents  more,  or  54  cents,  and 
the  profit  on  the  other  groups  proportionately  less. 

The  cost  data  on  this  flock  shows  that  although  the  latest  maturing 
group  ate  less  feed  per  bird,  the  owner  would  have  been  much  better 
off  financially  had  they  been  disposed  of  on  the  market  at  the  time 
of  segregation.  The  owner  of  such  birds  should  not  hesitate  because 
the  birds  are  small  and  light  and  will  bring  very  little  on  the  market. 
It  would  be  better  to  give  them  away  than  to  keep  them.  Considering 
the  returns  on  the  eight-month  period,  the  greater  mortality,  and 
other  indications  of  weak  vitality,  the  loss  on  such  birds  would  no 
doubt  be  greater  the  longer  they  were  kept.  Also  it  is  important  to 
consider  that  the  weaker  individuals  are  more  subject  to  infection 
and  parasitic  infestation. 

Culling  Data. — It  was  hoped  that  all  of  the  cooperators  would 
carry  the  test  through  for  a  twelve-month  period  and  if  possible  some 
might  be  induced  to  carry  the  same  birds  through  another  year  as 
segregated.  However,  at  the  end  of  the  ten-month  period  most  of  the 
cooperators  were  beginning  to  plan  on  culling  and  refilling  their 
houses  to  capacity.  So  on  June  15,  1923,  the  three  groups  in  the  flock 
on  which  cost  data  was  obtained  were  run  together  and  culled  by  the 
Agricultural  Extension  Service5  to  secure  further  data  on  this  basis. 

As  a  part  of  the  culling  work  the  entire  flock  was  again  segregated 
into  three  groups:  those  which  were  thought  to  be  worth  keeping  as 
breeders ;  those  which  were  worth  keeping  as  layers ;  and  those  which 
should  be  disposed  of  as  culls.  While  the  practice  of  selecting  breed- 
ers so  early  is  not  to  be  recommended,  it  was  done  in  this  case  at  the 
urgent  request  of  the  cooperator.  At  the  same  time  a  careful  record 
was  kept  of  the  number  of  the  earliest,  medium,  and  latest  maturing 
pullets  which  were  placed  in  each  of  the  three  groups.  Table  5  and 
figure  5  show  the  results  of  this  culling  and  the  percentage  of  the 
earliest,  medium,  and  latest  maturing  pullets  which  were  placed  in 
each  of  the  three  groups  of  breeders,  layers,  and  culls. 

It  is  interesting  to  note  that  half  of  the  latest  maturing  pullets 
which  were  placed  in  the  group  of  breeders,"  died  before  August  15, 
two  months  later.  This  indicates  a  lack  of  sufficient  vitality  to  main- 
tain heavy  production,  contrary  to  the  favorable  indications  at  the 
time  they  were  culled.  Similar  observations  were  also  made  by 
Kennard  and  Kempster  and  Henderson  in  their  work.     We  quote 


5  This  work  was  supervised  by  W.  E.  Newlon,   Extension  Poultry  Specialist, 
University  of  California. 


14 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


from  Kempster  and  Henderson6  as  follows :  ' '  The  early  layer  evidently 
had  the  ability  to  stand  up  better  under  the  strain  of  heavy  pro- 
duction. ' ' 

TABLE  5 

Culling  Data  on  One  of  the  Three-Group  Segregations 

Showing  the  percentage  of  breeders,  layers,  and  culls  obtained  from  each  of  the 

earliest,  medium,  and  latest  maturing  groups  and  the  entire  flock. 

Flock  culled  June  15. 


Group 

Earliest 
maturing 

Medium 
maturing 

Slowest 
maturing 

Entire 
flock 

Breeders 

per  cent 

34.8 
52.3 

12.8 

per  cent 

17.5 
51.7 
30.8 

per  cent 

4.0 
55.7 
40.2 

per  cent 

22.3 

Layers 

52.7 

Culls 

25.5 

Earli'esrr  Maturing    Medium  Maturing  Latest-  Maturing        Entire   Flock. 

|     |  Brcedei-s  £ZJ  Layers  g2  Culls 

Fig.  5. — Illustrating  table  5.  Culling  data  on  one  of  the  flocks  in  the  three- 
group  segregations  of  the  second  pullet  test.  The  flock  consisted  of  577  pullets. 
They  were  culled  June  15,  at  15  months  of  age. 

e  Op.  cit. 


BUL.  424]       RELATION   OF  RATE  OF   MATURITY  TO  EGG  PRODUCTION  15 


IMPORTANCE  OF  SEGREGATION 

Very  seldom,  at  least  under  commercial  conditions,  is  it  possible 
to  raise  a  flock  of  pullets  which  are  uniform  in  size  and  development. 
In  the  average  Single  Comb  White  Leghorn  pullet  flock  a  few  may 
start  to  lay  between  four  and  five  months,  the  majority  before  seven, 
and  some  not  until  from  eight  to  ten  months  of  age.  Consequently, 
in  any  consideration  of  the  problem  of  pullet  segregation  and  culling, 
emphasis  should  be  placed  on  the  value  of  segregation.  Pullets  which 
are  more  nearly  uniform  in  size  and  sexual  development  will  do  much 
better  when  placed  in  a  group  by  themselves.  This  is  particularly 
true  of  the  slower  developing  pullets.  It  is  almost  as  important  for 
the  commercial  poultryman  to  segregate  the  late  maturing  pullets 
from  the  early  maturing  pullets  at  four  and  one-half  to  six  months 
of  age,  as  it  is  to  segregate  the  cockerels  from  the  pullets  at  five  to 
eight  weeks  of  age.  Slower,  weaker  individuals  would  thus  have  a 
better  opportunity  at  feed  and  would  not  be  annoyed  and  bullied  by 
the  larger  individuals. 


FACTORS  INVOLVED  IN  RATE  OF  MATURITY 

In  the  discussion  thus  far  emphasis  has  been  placed  on  normal 
maturity.  It  is  probable  that  similar  results  would  be  obtained  where 
the  pullets  develop  more  slowly  than  normal.  But  it  is  doubtful  if 
the  same  results  would  be  obtained  where  the  pullets  are  stimulated 
into  sexual  maturity  before  they  have  attained  good  body  weight. 
In  the  latter  case  it  is  probable  that  the  earliest  maturing  birds  would 
be  inferior  at  least  to  the  medium-maturing  birds,  because  of  their 
tendency  to  be  smaller  and  weaker,  and  to  lay  smaller  eggs  for  a 
greater  period  at  the  start  and  throughout  their  lifetime.  There  are 
two  groups  of  factors  which  are  of  importance  in  affecting  the  rate 
of  maturity :  genetic  factors  and  physiological  factors. 

Genetic  factors  are  important  in  that  early  maturity  may  be 
effected  by  selection.  Except  for  a  small  percentage  of  early  freaks, 
inherent  early  maturity  is  very  desirable.  In  fact  early  maturity 
when  correlated  with  vigor  and  good  body  development  may  be  con- 
sidered as  an  indication  of  good  breeding.  This  emphasizes  the 
importance  of  pullet  segregation  in  the  selection  of  breeders. 

Among  physiological  factors,  both  retarding  and  abnormally  stim- 
ulating influences  are  detrimental  to   economical  results.     Physical 


16  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

growth  and  sexual  maturity  may  be  retarded  by  extreme  temperatures 
in  incubation  of  eggs  or  in  brooding  of  the  chicks;  crowding;  faulty 
ventilation,  such  as  lack  of  sufficient  fresh  air;  poor  sanitation;  or 
improper  feeding  which  fails  to  supply  the  necessary  nutrients  for 
proper  growth  during  the  brooding  period.  Parasitic  infestation, 
particularly  coccidia  and  round  worms,  serve  to  handicap  maturity. 
Late  hatched  chicks  (April  1  to  June  15)  often  mature  more  slowly 
than  those  hatched  earlier  (December  15  to  April  1).  The  principal 
stimulating  influence  is  the  feeding  of  an  unbalanced  ration  contain- 
ing too  much  animal  protein,  particularly  when  associated  with  some 
of  the  retarding  influences  which  result  in  sex  being  prematurely 
developed  before  good  body  development  is  obtained. 


RATE  OF  MATURITY  AS  RELATED  TO  SIZE  OF  EGGS 

The  pullet-segregation  tests  as  described  above  show  that  the  early 
maturing  birds  will  lay  a  larger  number  of  eggs.  However,  in  none 
of  these  tests  were  records  kept  on  the  comparative  size  of  eggs  laid 
by  birds  in  each  group.  Consequently,  the  relative  value  of  eggs 
laid  by  early  and  late  maturing  birds  was  not  definitely  known.  To 
obtain  information  on  this  subject  two  flocks  were  segregated  in  the 
early  fall  of  1924,  the  owners  of  which  agreed  to  keep  careful  records 
not  only  on  the  total  number  of  eggs  and  mortality  but  also  the 
relative  size  of  eggs  laid  by  each  group.  These  flocks  comprised  1621 
and  1070  pullets,  which  are  hereafter  referred  to  as  flocks  A  and  B 
respectively. 

Test,  Flock  A. — The  flock  comprising  1621  pullets  was  segregated 
on  August  21,  1924,  at  six  months  of  age ;  424  pullets,  the  largest  and 
earliest  maturing  in  the  flock,  were  placed  in  group  1 ;  417,  later  and 
medium-maturing,  were  placed  in  group  2 ;  and  780,  the  latest  matur- 
ing, were  placed  in  group  3.  Each  group  was  kept  in  a  separate 
house,  all  of  the  same  type  and  having  the  same  floor  space  per  bird. 
The  flock  owner  cooperated  by  keeping  very  careful  records  on  the 
three  groups  for  eight  months.  The  record  keeping  was  supervised 
very  closely  by  a  representative  of  the  Agricultural  Extension  Service 
and  the  records  collected  each  month.  Table  6  gives  a  detailed  sum- 
mary of  the  number  of  eggs  per  hen,  size  of  eggs,  value  of  eggs,  and 
mortality  in  each  group  during  the  eight-month  period  from  Septem- 
ber 1  to  April  30.  The  size  of  eggs  is  given  in  percentage ;  No.  1  eggs 
being  those  which  weighed  22  ounces  or  more  per  dozen;  No.  2,  from 
19  to  22  ounces ;  and  No.  3,  less  than  19  ounces  per  dozen.    The  value 


Bul.  424]       RELATION  OF  RATE  OF   MATURITY  TO  EGG  PRODUCTION 


17 


of  eggs  was  based  on  the  current  average  monthly  quotations  for  each 
size  of  eggs  as  paid  by  the  Poultry  Producers  of  Central  California 
to  producers  in  this  district  during  this  period. 

TABLE  6 
Pullet- Segregation  Test,  1924-25,  Flock  A 
Three-group  segregation  at  six  months  of  age. 


Eggs  per  pullet 

Size  of  eggs,  per  cent 

Value  of 
eggs 

Per  cent 
mortality 

Month 

a 

2 
a 

a 

3 

o 
0 

CO 

a 
a 

o 
0 

Group  1 

Group  2 

Group 

3 

a 
0 
o 

o 

a 
o 

u 

O 

CO 

a 
3 
o 

i-. 

O 

a 

3 

2 
O 

CM 

a 

2 
O 

CO 

No. 
1 

No. 
2 

No. 
3 

No. 
1 

No. 

2 

No. 
3 

No. 

1 

No. 
2 

No. 
3 

2 
o 

Sept 

12.7 

3.5 

.7 

3 

39 

58 

3 

43 

54 

4 

38 

58 

.30 

.08 

.02 

.0 

.0 

.2 

Oct 

13.4 

9.2 

6.2 

18 

60 

22 

20 

61 

19 

20 

62 

18 

.44 

.31 

.20 

.0 

.2 

.3 

Nov 

12.0 

12.5 

10.7 

44 

51 

5 

48 

49 

3 

60 

54 

6 

.46 

.49 

.41 

.2 

.0 

1.4 

Dec 

14.1 

14.5 

13.7 

68 

31 

70 

28 

4 

64 

35 

1 

.55 

.56 

.53 

.5 

.0 

.8 

Jan 

18.1 

16.6 

15.6 

75 

24 

77 

22 

1 

70 

29 

1 

.71 

.70 

.61 

.2 

1.0 

.4 

Feb 

17.4 

15.9 

15.2 

73 

26 

74 

25 

1 

68 

30 

2 

.47 

.43 

.41 

.2 

1.2 

,.1 

Mar 

18.0 

16.4 

16.0 

68 

31 

71 

28 

1 

66 

32 

2 

.41 

.38 

.37 

.2 

1.0 

1.6 

Apr 

7.0 

6.1 

6.0 

75 

24 

77 

22 

1 

72 

27 

1 

.16 

.14 

.14 

? 

? 

? 

Totals... 

112.7 

94.7 

84.1 

3.50 

3.09 

2.69 

1.3 

3.4 

4.8 

Note:  Group  1  comprised  424  earliest  maturing  pullets;  group  2,  417  medium-maturing  pullets; 
and  group  3,  780  latest  maturing  pullets. 

No.  1,  No.  2,  and  No.  3,  under  "Size  of  eggs,"  refer  to  the  22  ounces  and  over;  19  to  22  ounces;  and 
less  than  19-ounces  per  dozen  eggs,  respectively. 


TABLE  7 

Average  Number  of  Eggs  of  Each  Size  and  Total  Number  of  Eggs  by  Group, 

Pullet-Segregation  Test,  1924-25,  Elock  A 

Eight-month  period,  September  to  May. 


Group 

No.  1  eggs 
per  pullet 

No.  2  eggs 
per  pullet 

No.  3  eggs 
per  pullet 

Total  number  eggs 
all  sizes 

1 
2 
3 

61.4 
59.2 
50.5 

39.6 
31.0 
30.5 

11.7 
4.5 
3.2 

112.7 
94.7 
84.1 

Note:  Groups  1,  2,  and  3  refer  to  the  earliest  maturing,  medium-maturing  and  latest 
maturing  group,  respectively.  No.  1,  No.  2,  and  No.  3  eggs  weigh  22  ounces  and  over;  19  to 
22  ounces;   and  less  than  19  ounces  per  dozen  eggs,  respectively. 


Figure  6  shows: 

1.  The  total  average  number  of  No.  1,  No.  2,  and  No.  3  eggs  per 
bird  and  the  total  average  number  of  eggs  per  bird  laid  by  each  group. 

2.  The  percentage  of  No.  1,  No.  2,  and  No.  3  eggs  laid  by  each 
group,  based  on  the  average  production  in  each  group. 


18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


3.  The  total  value  per  bird  of  No.  1,  No.  2,  and  No.  3  eggs,  and 
the  total  value  of  all  eggs  per  bird  in  each  group. 

4.  The  average  mortality  in  each  group. 

The  earliest  maturing  pullets  (group  1)  in  flock  A  laid  a  larger 
number  of  each  size  of  eggs  and  consequently  returned  a  greater 
revenue  per  bird  than  the  later  maturing  pullets  (groups  2  and  3). 
However,  the  latest  maturing  birds  (group  3)  comprising  approxi- 
mately 50  per  cent  of  the  flock,  laid  a  larger  percentage  of  No.  1  eggs 
than  the  earliest  maturing,  which  included  approximately  25  per  cent 


94.7 


'A   mi 


62% 


35'A 


eo?0 


az% 


36% 


*3.50 


*3.0/ 


Wz 


*Z.&8 


%& 


Z.4 


1.3 


Group  I  GroupX.    Group  &       Group    /     Group  Z    Group  3         Group/     Group  X.    Group  3         Group  t    Group  Z     Group  3 

lbi-at  Eggs  Per  Po/Ief  Size  of  Eggs  by  6roup)\       Value  of  Eggs  Per  Can+  Morfatiiy 

(ZZ1  No.  /  Eggs  CH3   No.  Z  Eggs  E3  No. 3  Eggs 

Fig.  6. — Illustrating  tables  6  and  7.  Total  number,  size,  and  value  of  eggs, 
and  mortality,  in  earliest  (1),  medium  (2),  and  latest  maturing  groups  (3); 
flock  A,  of  three-group  segregation  in  pullet-test,  1924-25. 


of  the  flock,  although  group  1  laid  a  larger  number  of  each  size  of 
eggs  than  group  3.  It  will  also  be  noted  that  group  2,  the  second 
earlier  maturing  birds,  comprising  25  per  cent  of  the  flock,  laid  not 
only  a  larger  number  of  eggs  per  bird  of  all  sizes  than  group  3,  but 
also  a  larger  percentage  of  No.  1  and  No.  3  eggs.  Therefore,  it  would 
appear  that  the  earliest  and  the  latest  maturing  pullets  lay  relatively 
smaller  eggs  than  the  medium-maturing  pullets. 

Test,  Flock  B. — The  second  flock,  comprising  1070  pullets,  was 
segregated  at  six  months  and  ten  days  of  age,  on  September  4,  1924, 
into  three  groups,  as  follows:  745,  hereafter  designated  as  group  1, 
the  earlier  maturing  birds;  270  (group  2),  later  maturing,  and  55 
(group  3),  the  latest  maturing.  The  owner  was  advised  by  the  repre- 
sentative of  the  Agricultural  Extension  Service  making  the  segre- 
gation to  sell  the  55  latest  maturing  birds  as  culls.    The  owner,  how- 


BUL.  424]       RELATION  OF  RATE  OF  MATURITY  TO  EGG  PRODUCTION 


19 


ever,  decided  to  keep  these  as  a  part  of  the  test  but  no  definite  pro- 
duction records  were  kept  on  this  group.  On  July  8,  1925,  only  13 
of  the  birds  remained  in  the  cull  group,  the  other  42  having  died 
during  the  ten-month  period.  Complete  records  similar  to  those  kept 
on  test  flock  A  were  kept  on  the  first  two  groups  of  this  flock  during 
nearly  a  complete  nine-month  period,  from  September  5  to  May  31, 
and  are  summarized  in  table  8. 

TABLE  8 

Pullet-Segregation  Test,  1924-25,  Flock  B 

Three-group  segregation.     Segregated  at  six  months  ten  days  of  age.     Group  1, 

745  earlier  maturing  and  group  2,  270  later  maturing  pullets. 

Eecords  on  55  latest  maturing  pullets  not  included. 


Eggs  per  hen 

Size  of  eggs,  per  cent 

Value  of 
eggs 

Per  cent 
mortality 

Month 

Group 
1 

Group 
2 

Group  1 

Group  2 

Group 
1 

Group 
2 

Group 
1 

Group 

No.  1 

No.  2 

No.  3 

No.l 

No.  2 

No.  3 

2 

September 

9.9 
11.2 
12.1 
14.0 
14.4 
14.0 
15.4 
12.2 
11.28 

.4 
7.9 
8.1 
10.3 
12.1 
9.9 
11.3 
8.4 
9.34 

5 
18 

47 
71 
80 
81 
74 
71 
74 

45 

59 
49 
28 
20 
19 
29 
29 
26 

50 

23 

4 

1 
.3 

8 
33 
42 
65 
71 
75 
71 
70 
70 

49 
53 
49 
33 
28 
25 
29 
30 
30 

43 
14 

9 
2 

.7 

S  .26 
.36 
.51 
.54 
.58 
.38 
.36 
.27 
.27 

$  .01 
.28 
.31 
.40 
.50 
.27 
.26 
.19 
.23 

.8 
.8 
.8 

3.1 

1. 

1.39 
.7 

1.8 

1.5 

0 

.7 

1.1 

2.3 

.4 

1.93 

1.2 

1.6 

4.1 

Totals 

115.5 

77.7 

$3.53 

$2.45 

11.9 

13.3 

58 

33.3 

8.7 

56.1 

36.2 

7.7 

In  flock  B  the  earliest  maturing  pullets  (comprising  approximately 
70  per  cent  of  the  entire  flock)  laid  a  higher  average  percentage  of 
No.  1  eggs  and  also  a  higher  percentage  of  No.  3  eggs  than  those  in 
group  2  (comprising  about  25  per  cent  of  the  flock).  The  earliest 
maturing  pullets  laid  a  smaller  percentage  of  medium-sized  or  No.  2 
eggs.  Otherwise,  the  results  in  flock  B  are  similar  to  those  obtained 
in  flock  A. 

It  may  be  concluded  from  these  tests  that  the  earlier  maturing 
birds  in  a  pullet  flock,  as  indicated  by  physical  and  sexual  develop- 
ment at  approximately  six  months  of  age,  will  lay  a  larger  number 
of  each  size  of  eggs  than  the  later  maturing  birds  in  the  flock.  A 
small  percentage  of  the  earliest  maturing  pullets  will  lay  relatively 
smaller  eggs  than  the  later  maturing  birds,  on  the  basis  of  relative 
number  of  the  different  sizes  of  all  eggs  laid.    The  medium-maturing 


20  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

pullets  will  lay  a  larger  percentage  of  large  eggs  than  the  earliest 
and  latest  maturing  and  a  larger  number  of  eggs  than  the  latest 
maturing  pullets.  However,  it  is  apparent  that  the  earlier  maturing 
pullets  will  return  a  greater  gross  revenue  from  sale  of  eggs  than  the 
later  maturing  pullets. 

Hen  Culling  Test. — On  July  8,  1925,  the  hens  in  groups  1  and  2 
of  test  flock  B  were  combined  in  the  same  house  and  culled  by  a 
representative  of  the  Agricultural  Extension  Service.  This  work  was 
checked  by  two  persons  well  trained  in  poultry  culling.  At  this  time 
birds  in  this  flock  were  approximately  sixteen  months  of  age.  The 
methods  used  in  culling  were  those  recommended  by  the  University 
of  California  and  based  on  an  interpretation  of  the  physical  character- 
istics of  each  bird  handled  individually.  A  total  of  26  per  cent  of 
the  flock  was  culled  out  as  unprofitable  producers.  On  checking  the 
number  of  early  maturing  and  medium-maturing  pullets  in  this  26 
per  cent  it  was  found  that  only  18  per  cent  of  the  early  maturing 
pullets  (group  1  in  the  test)  had  been  culled  out  as  against  50  per  cent 
of  the  later  maturing  (group  2  in  the  test). 


CONCLUSIONS 

1.  Rate  of  maturity  is  a  good  gauge  of  potential  egg-laying  ability 
of  Single  Comb  White  Leghorn  pullets  in  commercial  flocks. 

2.  In  a  normally  maturing  Single  Comb  White  Leghorn  flock  the 
earlier  maturing  pullets  will  lay  a  larger  number  of  eggs  during  the 
first  year's  production,  and  very  probably  thereafter. 

3.  The  later  maturing  pullets  are  slower  to  start  and  quicker  to 
drop  in  egg  production. 

4.  The  earlier  maturing  pullet  possesses  greater  vitality. 

5.  The  easiest  and  probably  the  best  time  to  segregate  pullets  is  at 
four  and  one-half  to  six  months  of  age  or  at  about  the  time  5  to  10 
per  cent  of  the  birds  are  beginning  to  lay. 

6.  Each  of  the  segregated  groups,  particularly  the  later  maturing 
pullets,  will  develop  much  better  after  segregation. 

7.  Pullet  segregation  should  be  practiced  by  commercial  poultry- 
men  where  it  is  possible  to  obtain  the  equipment  without  too  much 
trouble  and  expense. 

8.  Segregation  assists  in  a  more  systematic  and  intelligent  culling 
of  the  flock,  the  following  summer. 


BUL.  424]       RELATION  OF  RATE  OF  MATURITY  TO  EGG  PRODUCTION  21 

9.  Segregation  assists  in  selecting  the  best  birds  in  the  flock  for 
breeding  purposes,  since  a  large  percentage  of  the  strongest  and 
heaviest  individuals  and  the  most  consistent  egg  producers  come  from 
the  earlier  maturing  pullets. 

10.  At  least  10  to  15  per  cent  of  the  latest  maturing  birds  in  the 
average  Single  Comb  White  Leghorn  pullet  flock  should  be  culled  out 
at  four  and  one-half  to  six  months  of  age  and  disposed  of  as  unprofit- 
able egg  producers. 

11.  The  earlier  maturing  pullets  lay  a  greater  number  of  each  size 
of  eggs  than  those  maturing  later. 

12.  Medium-maturing  pullets  lay  a  greater  percentage  of  large 
eggs  than  either  the  earliest  or  latest  maturing  pullets,  and  a  greater 
number  of  eggs  than  the  latest  maturing. 

13.  The' earlier  maturing  pullets  return  a  greater  revenue  from 
sale  of  eggs  than  the  later  maturing  pullets. 


ACKNOWLEDGMENTS 

Much  credit  is  due  the  cooperators  who  permitted  the  use  of  their 
flocks  and  kept  the  records,  particularly  Mr.  George  E.  Burlingame, 
of  Sebastopol,  who  supplied  the  cost  data,  and  Mr.  Otto  Palm,  of 
Windsor,  and  Mr.  Oscar  Durham,  of  Petaluma,  who  supplied  the  data 
on  size  of  eggs. 

Furthermore,  the  writer  is  indebted  to  R.  B.  Easson,  former 
Extension  Poultry  Specialist,  and  W.  E.  Newlon,  Extension  Poultry 
Specialist,  for  assistance  in  segregating  and  culling  certain  flocks  as 
indicated. 


LIST  OF  PUBLICATIONS  AVAILABLE  FOR  FREE  DISTRIBUTION 


No. 

253.   Irrigation   and   Soil   Conditions   in  the 
Sierra   Nevada   Foothills,    California. 

261.  Melaxuma    of    the    Walnut,     "Juglans 

regia." 

262.  Citrus   Diseases   of   Florida    and   Cuba 

Compared  with  Those  of  California. 

263.  Size   Grades   for  Ripe   Olives. 

268.   Growing  and  Grafting  Olive  Seedlings. 
273.   Preliminary  Report  on  Kearney  Vine- 
yard  Experimental   Drain. 

275.  The     Cultivation     of     Belladonna     in 

California. 

276.  The  Pomegranate. 

277.  Sudan    Grass. 

278.  Grain    Sorghums. 

279.  Irrigation   of  Rice   in   California. 
283.   The  Olive  Inserts  of  California. 
294.   Bean   Culture  in   California. 

304.  A  Study  of  the  Effects  of  Freezes  on 

Citrus    in    California. 
310.   Plum    Pollination. 

312.  Mariout  Barley. 

313.  Pruning      Young      Deciduous      Fruit 

Trees. 
319.   Caprifigs    and    Caprification. 

324.  Storage  of   Perishable  Fruit  at  Freez- 

ing Temperatures. 

325.  Rice     Irrigation     Measurements     and 

Experiments    in    Sacramento   Valley, 

1914-1919. 
328.   Prune   Growing   in   California. 
331.  Phylloxera-Resistant    Stocks. 
335.   Cocoanut   Meal    as   a   Feed   for   Dairy 

Cows   and    Other   Livestock. 

339.  The    Relative    Cost    of    Making    Logs 

from   Small   and  Large  Timber. 

340.  Control     of     the     Pocket     Gopher     in 

California. 

343.  Cheese    Pests    and    Their    Control. 

344.  Cold    Storage   as    an   Aid  to    the   Mar- 

keting of  Plums. 

346.  Almond    Pollination. 

347.  The  Control  of  Red  Spiders  in  Decid- 

uous Orchards. 

348.  Pruning  Young  Olive  Trees. 

349.  A    Study    of    Sidedraft    and    Tractor 

Hitches. 

350.  Agriculture      in      Cut-over      Redwood 

Lands. 

352.  Further  Experiments  in  Plum  Pollina- 

tion. 

353.  Bovine   Infectious   Abortion. 

354.  Results  of  Rice  Experiments  in   1922. 

357.  A    Self-mixing    Dusting    Machine    for 

Applying      Dry      Insecticides      and 
Fungicides. 

358.  Black    Measles,    Water    Berries,     and 

Related  Vine  Troubles. 

361.  Preliminary   Yield   Tables   for    Second 

Growth   Redwood. 

362.  Dust  and  the  Tractor  Engine. 

363.  The  Pruning  of  Citrus  Trees  in  Cali- 

fornia. 

364.  Fungicidal   Dusts    for   the    Control    of 

Bunt. 

365.  Avocado  Culture  in  California. 

366.  Turkish  Tobacco  Culture,   Curing  and 

Marketing. 

367.  Methods  of  Harvesting  and  Irrigation 

in   Relation  of  Mouldy  Walnuts. 

368.  Bacterial  Decomposition  of  Olives  dur- 

ing Pickling. 

369.  Comparison     of     Woods     for     Butter 

Boxes. 


BULLETINS 
No. 


370. 
371. 


372. 


373. 
374. 


375. 

376. 

377. 
379. 
380. 

381. 

382. 

383. 

385. 
386. 

387. 
388. 

389. 
390. 

391. 

392. 
393. 
394. 

395. 
396. 

397. 

398. 
399. 


400. 
401. 

402. 
403. 
404. 
405. 
406. 
407. 


408. 
409. 


410. 


412. 


413 


414, 


Browning  of  Yellow  Newtown  Apples. 
The    Relative    Cost    of    Yarding    Small 

and   Large   Timber. 
The  Cost  of  Producing  Market  Milk  and 
Butterfat  on  246  California  Dairies. 
Pear   Pollination. 

A  Survey  of  Orchard  Practices  in  the 
Citrus    Industry  of    Southern    Cali- 
fornia. 
Results    of    Rice    Experiments    at   Cor- 

tena,    1923. 
Sun-Drying  and  Dehydration  of  Wal- 
nuts. 
The  Cold   Storage  of  Pears. 
Walnut   Culture   in   California. 
Growth    of    Eucalyptus    in    California 

Plantations. 
Growing     and     Handling     Asparagus 

Crowns. 
Pumping    for    Drainage    in    the    San 

Joaquin    Valley,    California. 
Monilia  Blossom  Blight    (Brown  Rot) 

of  Apricot. 
Pollination    of   the    Sweet    Cherry. 
Pruning     Bearing     Deciduous     Fruit 

Trees. 
Fig   Smut. 

The    Principles    and   Practice   of    Sun- 
drying  Fruit. 
Berseem  or   Egyptian   Clover. 
Harvesting    and    Packing    Grapes    in 

California. 
Machines  for  Coating  Seed  Wheat  with 

Copper   Carbonate   Dust. 
Fruit    Juice    Concentrates. 
Crop  Sequences  at  Davis. 
Cereal   Hay   Production   in   California. 

Feeding  Trials  with  Cereal  Hay. 
Bark   Diseases   of   Citrus  Trees. 
The    Mat    Bean    (Phaseolus    aconitifo- 

lius). 
Manufacture   of  Roquefort  Type  Cheese 

from   Goat's   Milk. 
Orchard  Heating  in  California. 
The    Blackberry    Mite,    the    Cause    of 
Redberry    Disease    of    the    Himalaya 
Blackberry,    and   its   Control. 
The  Utilization  of  Surplus  Plums. 
Cost    of    Work    Horses    on    California 

Farms. 
The  Codling  Moth  in  Walnuts. 
Farm-Accounting  Associations. 
The  Dehydration  of  Prunes. 
Citrus  Culture  in  Central  California. 
Stationary  Spray  Plants  in  California. 
Yield,    Stand    and  Volume    Tables    for 
White    Fir    in    the    California    Pine 
Region. 
Alternaria  Rot  of  Lemons. 
The  Digestibility  of  Certain  Fruit  By- 
products   as    Determined    for    Rumi- 
nants. 
Factors  Affecting  the  Quality  of  Fresh 

Asparagus  after  it  is  Harvested. 
Paradichlorobenzene    as    a    Soil    Fumi- 

gant. 
A  Study  of  the  Relative  Values  of  Cer- 
tain Root  Crops  and  Salmon   Oil   as 
Sources  of  Vitamin  A  for  Poultry. 
The    California    Poultry    Industry;     a 

Statistical  Study. 
Planting   and  Thinning  Distances   for 
Deciduous  Fruit  Trees. 


No. 

87.  Alfalfa.  „      „ 

117.  The    Selection    and    Cost    of    a    Small 

Pumping   Plant. 
127.  House    Fumigation. 
129.  The  Control  of   Citrus   Insects. 
136.  Melilotus    indica    as    a    Green-Manure 

Crop  for  California. 
144.   Oidium    or    Powdery    Mildew    of    the 

Vine. 
157.   Control  of  the  Pear  Scab.      > 
160.   Lettuce  Growing  in  California. 
164.    Small  Fruit  Culture  in  California. 
166.   The   County  Farm  Bureau. 
170.   Fertilizing     California     Soils     for     the 

1918   Crop.  tt 

173.  The    Construction    of    the    Wood-Hoop 

Silo.  .      „  ,.,       . 

178.  The   Packing  of  Apples  m   California. 

179.  Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
190.  Agriculture  Clubs  in  California. 
199.   Onion    Growing   in    California. 

202.  County   Organizations   for   Rural   lire 

Control. 

203.  Peat   as    a   Manure    Substitute. 

209    The  Function  of  the  Farm  Bureau. 
210.   Suggestions  to  the  Settler  in  California. 
212.   Salvaging    Rain-Damaged    Prunes. 
215.   Feeding  Dairy  Cows  in  California. 
217.  Methods   for   Marketing  Vegetables   in 

California. 
220.  Unfermented   Fruit  Juices. 
228.  Vineyard  Irrigation  in  Arid  Climates. 

230.  Testing  Milk,    Cream,    and   Skim   Milk 

for  Butterfat. 

231.  The    Home   Vineyard. 

232.  Harvesting    and    Handling    California 

Cherries    for    Eastern    Shipment. 

234.  Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 

235.  Soil    Analysis     and     Soil    and     Plant 

Inter-relations. 

236.  The    Common    Hawks     and    Owls    of 

California    from    the    Standpoint    of 
the  Rancher. 

237.  Directions  for  the  Tanning  and  Dress- 

ing of  Furs. 

238.  The  Apricot  in  California. 

239.  Harvesting     and     Handling     Apricots 

and  Plums  for  Eastern  Shipment. 

240.  Harvesting    and    Handling    Pears    for 

Eastern   Shipment. 

241.  Harvesting  and  Handling  Peaches  for 

Eastern   Shipment. 

243.  Marmalade  Juice  and  Jelly  Juice  from 

Citrus  Fruits. 

244.  Central  Wire  Bracing  for  Fruit  Trees. 

245.  Vine   Pruning   Systems. 

247.  Colonization  .  and   Rural   Development. 

248.  Some    Common    Errors    in   Vine  Prun- 

ing and  Their  Remedies. 

249.  Replacing  Missing  Vines. 

250.  Measurement   of    Irrigation   Water   on 

the  Farm. 

252.  Supports  for  Vines. 

253.  Vineyard  Plans. 

254.  The  Use  of  Artificial  Light  to  Increase 

Winter    Egg    Production. 


CIRCULARS 
No. 
255. 


256. 
257. 
258. 
259. 
261. 
262. 
263. 
264. 

265. 
266. 

267. 

269. 

270. 
272. 

273. 
274. 

276. 
277. 

278. 

279. 

281. 


282. 

283. 

284. 
285. 
286. 
287. 
288. 
289. 
290. 
291. 

292. 
293. 
294. 
295. 

296. 

298. 

299. 
300. 
301, 
302. 
303. 

304. 
305. 
306. 

307. 

308. 


Leguminous  Plants  as  Organic  Fertil- 
izer   in    California    Agriculture. 

The    Control   of   Wild   Morning    Glory. 

The  Small-Seeded  Horse  Bean. 

Thinning   Deciduous   Fruits. 

Pear  By-products. 

Sewing  Grain  Sacks. 

Cabbage   Growing  in   California. 

Tomato  Production  in   California. 

Preliminary  Essentials  to  Bovine 
Tuberculosis  Control. 

Plant   Disease   and   Pest   Control. 

Analyzing  the  Citrus  Orchard  by 
Means   of    Simple   Tree    Records. 

The  Tendency  of  Tractors  to  Rise  in 
Front;    Causes   and   Remedies. 

An  Orchard  Brush  Burner. 

A  Farm  Septic  Tank. 

California  Farm  Tenancy  and  Methods 
of  Leasing. 

Saving  the   Gophered  Citrus  Tree. 

Fusarium  Wilt  of  Tomato  and  its  Con- 
trol by  Means  of  Resistant  Varieties. 

Home  Canning. 

Head,  Cane,  and  Cordon  Pruning  of 
Vines. 

Olive  Pickling  in  Mediterranean  Coun- 
tries. 

The  Preparation  and  Refining  of  Olive 
Oil   in    Southern    Europe. 

The  Results  of  a  Survey  to  Determine 
the  Cost  of  Producing  Beef  in  Cali- 
fornia. 

Prevention  of  Insect  Attack  on  Stored 
Grain. 

Fertilizing  Citrus  Trees  in  California. 

The  Almond   in   California. 

Sweet  Potato  Production  in  California. 

Milk  Houses  for  California  Dairies. 

Potato   Production   in   California. 

Phylloxera  Resistant  Vineyards. 

Oak  Fungus  in  Orchard  Trees. 

The  Tangier  Pea. 

Blackhead  and  Other  Causes  of  Loss 
of  Turkeys  in  California. 

Alkali  Soils. 

The    Basis    of   Grape    Standardization. 

Propagation   of   Deciduous   Fruits. 

The  Growing  and  Handling  of  Head 
Lettuce  in   California. 

Control  of  the  California  Ground 
Squirrel. 

The  Possibilities  and  Limitations  of 
Cooperative   Marketing. 

Poultry   Breeding   Records. 

Coccidiosis  of  Chickens. 

Buckeye  Poisoning  of  the  Honey  Bee. 

The   Sugar  Beet   in   California. 

A  Promising  Remedy  for  Black  Measles 
of  the  Vine. 

Drainage  on  the  Farm. 

Liming  the  Soil. 

A  General  Purpose  Soil  Auger  and  its 
Use  on  the  Farm. 

American    Foulbrood   and  its   Control. 

Cantaloupe  Production  in  California. 


The  publications  listed  above  may  be  had  by  addressing 

College  of  Agriculture, 

University  of  California, 

Berkeley,  California. 

15m-5,'27 


